Mike,
I found this forum invaluable in restoring my CB350 twin. I searched all over the internet, and while I did find a couple other forums dedicated to Honda twins, none were nearly as good as this one.
I would discourage you from starting a new forum, though. Here's why:
Part of the reason that we find so much help at SOHC4 for our twins, despite the fact this forum is not dedicated to twins, is that so many owners of single cam fours "graduated" to them after learning to ride on twins. As a result, this forum is full of guys who may ride SOHC4s now, but also have deep knowledge of the twins. Many of them (like me) still ride both fours and twins.
If you start your own site, dedicated to twins alone, it may not be frequented by as many helpful folks, since it will draw only twin owners. It is unlikely that you will get much of a contingent of former twin owners, like this site has.
Just my 2 cents.
BTW, I never got the sense while I was restoring my CB350 that anyone around here was annoyed by my twin questions. I sure hope they weren't, 'cuz I just tonight started a CL450 restoration! I'll be back . . . with more twin questions!